Method for reporting channel state information in wireless communication system and apparatus therefor

ABSTRACT

The present disclosure provides a method for reporting CSI in a wireless communication system. In the present disclosure, a method for reporting channel state information (CSI) in a wireless communication system, which is performed by a UE includes: receiving, from an eNB, downlink control information (DCI) indicating activation of semi-persistent (SP) CSI reporting, in which the downlink control information is scrambled with a specific RNTI distinguished from a Cell-Radio Network Temporary Identity (C-RNTI); and reporting, to the eNB, the semi-persistent CSI through a physical uplink shared channel (PUSCH) based on the received downlink control information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of Ser. No. 16/665,541,filed on Oct. 28, 2019, which is a continuation of InternationalApplication No. PCT/KR2018/004974, filed on Apr. 27, 2018, which claimsthe benefit of U.S. Provisional Application No. 62/491,322, filed onApr. 28, 2017, U.S. Provisional Application No. 62/501,080, filed on May3, 2017, and U.S. Provisional Application No. 62/565,185, filed on Sep.29, 2017, the contents of which are all hereby incorporated by referenceherein in their entirety.

The present disclosure relates to a wireless communication system, andmore particularly, to a method for reporting channel state information(CSI) and an apparatus for supporting the same.

BACKGROUND ART

Mobile communication systems have been generally developed to providevoice services while guaranteeing user mobility. Such mobilecommunication systems have gradually expanded their coverage from voiceservices through data services up to high-speed data services. However,as current mobile communication systems suffer resource shortages andusers demand even higher-speed services, development of more advancedmobile communication systems is needed.

The requirements of the next-generation mobile communication system mayinclude supporting huge data traffic, a remarkable increase in thetransfer rate of each user, the accommodation of a significantlyincreased number of connection devices, very low end-to-end latency, andhigh energy efficiency. To this end, various techniques, such as smallcell enhancement, dual connectivity, massive multiple input multipleoutput (MIMO), in-band full duplex, non-orthogonal multiple access(NOMA), supporting super-wide band, and device networking, have beenresearched.

SUMMARY

The present disclosure provides a method for indicating activation ordeactivation of semi-persistent (SP) CSI reporting through a PUSCH.

Furthermore, the present disclosure provides a method for reportingsemi-persistent (SP) CSI reporting through a PUSCH and/or a PUCCH.

Further, the present disclosure provides a method for solving, when acollision between a PUSCH resource for CSI reporting and a specificuplink resource occurs, solving the collision.

The technical objects of the present disclosure are not limited to theaforementioned technical objects, and other technical objects, which arenot mentioned above, will be apparently appreciated by a person havingordinary skill in the art from the following description.

In the present disclosure, a method for reporting channel stateinformation (CSI) in a wireless communication system, which is performedby a UE includes: receiving, from an eNB, downlink control information(DCI) indicating activation of semi-persistent (SP) CSI reporting, inwhich the downlink control information is scrambled with a specific RNTIdistinguished from a Cell-Radio Network Temporary Identity (C-RNTI); andreporting, to the eNB, the semi-persistent CSI through a physical uplinkshared channel (PUSCH) based on the received downlink controlinformation.

Further, in the present disclosure, the SP CSI reporting includes firstSP CSI reporting and second SP CSI reporting.

Further, in the present disclosure, the method further includesreceiving, from the eNB, a PUSCH resource for reporting the SP CSI.

Further, in the present disclosure, when the PUSCH resource collideswith a specific uplink resource, the SP CSI is reported to the eNBthrough a physical uplink control channel (PUCCH).

Further, in the present disclosure, the specific uplink resource is thePUCCH resource or the PUSCH resource on a mini-slot.

Further, in the present disclosure, the SP CSI through the PUCCH isreported in a slot related to the collision.

Further, in the present disclosure, the method further includesdetermining an uplink resource to perform the SP CSI reporting.

Further, when the DCI is uplink DCI, the SP CSI is reported through thePUSCH.

Further, in the present disclosure, a UE reporting channel stateinformation (CSI) in a wireless communication system includes: a radiofrequency (RF) module for transmitting and receiving a radio signal; anda processor functionally connected with the RF module, in which theprocessor is configured to receive, from an eNB, downlink controlinformation (DCI) indicating activation of semi-persistent (SP) CSIreporting, in which the downlink control information is scrambled with aspecific RNTI distinguished from a Cell-Radio Network Temporary Identity(C-RNTI), and report, to the eNB, the semi-persistent CSI through aphysical uplink shared channel (PUSCH) based on the received downlinkcontrol information.

According to the present disclosure, when an indication for activationor deactivation of SP CSI reporting is performed by DCI, the DCI isscrambled with RNTI apart from C-RNTI or SPS-C-RNTI, thereby reducingpower consumption of a terminal.

Furthermore, according to the present disclosure, when a PUSCH resourcefor the SP CSI reporting and a specific resource having a higherpriority than the PUSCH collide with each other, transmission in thespecific resource having the high priority is performed, therebyenhancing system performance.

Advantages which can be obtained in the present disclosure are notlimited to the aforementioned effects and other unmentioned advantageswill be clearly understood by those skilled in the art from thefollowing description.

DESCRIPTION OF DRAWINGS

The accompanying drawings, that are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of the present specification, illustrate embodiments of theinvention and together with the description serve to explain variousprinciples of the invention.

FIG. 1 illustrates an example of an overall structure of a new radio(NR) system to which a method proposed by the present specification isapplicable.

FIG. 2 illustrates a relationship between an uplink frame and a downlinkframe in a wireless communication system to which a method proposed bythe present specification is applicable.

FIG. 3 illustrates an example of a resource grid supported in a wirelesscommunication system to which a method proposed by the presentspecification is applicable.

FIG. 4 illustrates examples of a resource grid per antenna port andnumerology to which a method proposed by the present specification isapplicable.

FIG. 5 illustrates an example of a block diagram of a transmittercomposed of an analog beamformer and an RF chain.

FIG. 6 illustrates an example of a block diagram of a transmittercomposed of a digital beamformer and an RF chain.

FIG. 7 illustrates an example of an analog beam scanning schemeaccording to various embodiments of the present disclosure.

FIG. 8 illustrates an example of a PUSCH CSI reporting mode.

FIG. 9 illustrates an example of a PUCCH CSI reporting mode.

FIG. 10 illustrates an example of a self-contained subframe structure towhich a method proposed by the present specification is applicable.

FIG. 11 is a flow chart illustrating an example of a UE operationperforming CSI reporting proposed by the present specification.

FIG. 12 is a block diagram illustrating a configuration of a wirelesscommunication device according to an embodiment of the presentdisclosure.

FIG. 13 is a block diagram illustrating a configuration of acommunication device according to an embodiment of the presentdisclosure.

FIG. 14 illustrates an example of a radio frequency (RF) module of awireless communication device to which a method proposed by the presentspecification is applicable.

FIG. 15 illustrates another example of an RF module of a wirelesscommunication device to which a method proposed by the presentspecification is applicable.

DETAILED DESCRIPTION

Some embodiments of the present disclosure are described in detail withreference to the accompanying drawings. A detailed description to bedisclosed along with the accompanying drawings is intended to describesome exemplary embodiments of the present disclosure and is not intendedto describe a sole embodiment of the present disclosure. The followingdetailed description includes more details in order to provide fullunderstanding of the present disclosure. However, those skilled in theart will understand that the present disclosure may be implementedwithout such more details.

In some cases, in order to avoid making the concept of the presentdisclosure vague, known structures and devices are omitted or may beshown in a block diagram form based on the core functions of eachstructure and device.

In the present disclosure, a base station has the meaning of a terminalnode of a network over which the base station directly communicates witha terminal. In this document, a specific operation that is described tobe performed by a base station may be performed by an upper node of thebase station according to circumstances. That is, it is evident that ina network including a plurality of network nodes including a basestation, various operations performed for communication with a terminalmay be performed by the base station or other network nodes other thanthe base station. The base station (BS) may be substituted with anotherterm, such as a fixed station, a Node B, an eNB (evolved-NodeB), a basetransceiver system (BTS), or an access point (AP). Furthermore, theterminal may be fixed or may have mobility and may be substituted withanother term, such as user equipment (UE), a mobile station (MS), a userterminal (UT), a mobile subscriber station (MSS), a subscriber station(SS), an advanced mobile station (AMS), a wireless terminal (WT), amachine-type communication (MTC) device, a machine-to-Machine (M2M)device, or a device-to-device (D2D) device.

Hereinafter, downlink (DL) means communication from a base station toUE, and uplink (UL) means communication from UE to a base station. InDL, a transmitter may be part of a base station, and a receiver may bepart of UE. In UL, a transmitter may be part of UE, and a receiver maybe part of a base station.

Specific terms used in the following description have been provided tohelp understanding of the present disclosure, and the use of suchspecific terms may be changed in various forms without departing fromthe technical sprit of the present disclosure.

The following technologies may be used in a variety of wirelesscommunication systems, such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and non-orthogonalmultiple access (NOMA). CDMA may be implemented using a radiotechnology, such as universal terrestrial radio access (UTRA) orCDMA2000. TDMA may be implemented using a radio technology, such asglobal system for mobile communications (GSM)/general packet radioservice (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA maybe implemented using a radio technology, such as Institute of electricaland electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),IEEE 802.20, or evolved UTRA (E-UTRA). UTRA is part of a universalmobile telecommunications system (UMTS). 3rd generation partnershipproject (3GPP) Long term evolution (LTE) is part of an evolved UMTS(E-UMTS) using evolved UMTS terrestrial radio access (E-UTRA), and itadopts OFDMA in downlink and adopts SC-FDMAin uplink. LTE-advanced(LTE-A) is the evolution of 3GPP LTE.

Embodiments of the present disclosure may be supported by the standarddocuments disclosed in at least one of IEEE 802, 3GPP, and 3GPP2, thatis, radio access systems. That is, steps or portions that belong to theembodiments of the present disclosure and that are not described inorder to clearly expose the technical spirit of the present disclosuremay be supported by the documents. Furthermore, all terms disclosed inthis document may be described by the standard documents.

In order to more clarify a description, 3GPP LTE/LTE-A is chieflydescribed, but the technical characteristics of the present disclosureare not limited thereto.

DEFINITION OF TERMS

eLTE eNB: An eLTE eNB is an evolution of an eNB that supports aconnection for an EPC and an NGC.

gNB: Anode for supporting NR in addition to a connection with an NGC

New RAN: A radio access network that supports NR or E-UTRA or interactswith an NGC

Network slice: A network slice is a network defined by an operator so asto provide a solution optimized for a specific market scenario thatrequires a specific requirement together with an inter-terminal range.

Network function: A network function is a logical node in a networkinfra that has a well-defined external interface and a well-definedfunctional operation.

NG-C: A control plane interface used for NG2 reference point between newRAN and an NGC

NG-U: A user plane interface used for NG3 reference point between newRAN and an NGC

Non-standalone NR: A deployment configuration in which a gNB requires anLTE eNB as an anchor for a control plane connection to an EPC orrequires an eLTE eNB as an anchor for a control plane connection to anNGC

Non-standalone E-UTRA: A deployment configuration an eLTE eNB requires agNB as an anchor for a control plane connection to an NGC.

User plane gateway: A terminal point of NG-U interface

General System

FIG. 1 is a diagram illustrating an example of an overall structure of anew radio (NR) system to which a method proposed by the presentdisclosure may be implemented.

Referring to FIG. 1, an NG-RAN is composed of gNBs that provide an NG-RAuser plane (new AS sublayer/PDCP/RLC/MAC/PHY) and a control plane (RRC)protocol terminal for a UE (User Equipment).

The gNBs are connected to each other via an Xn interface.

The gNBs are also connected to an NGC via an NG interface.

More specifically, the gNBs are connected to a Access and MobilityManagement Function (AMF) via an N2 interface and a User Plane Function(UPF) via an N3 interface.

NR (New Rat) Numerology and Frame Structure

In the NR system, multiple numerologies may be supported. Thenumerologies may be defined by subcarrier spacing and a CP (CyclicPrefix) overhead. Spacing between the plurality of subcarriers may bederived by scaling basic subcarrier spacing into an integer N (or μ). Inaddition, although a very low subcarrier spacing is assumed not to beused at a very high subcarrier frequency, a numerology to be used may beselected independent of a frequency band.

In addition, in the NR system, a variety of frame structures accordingto the multiple numerologies may be supported.

Hereinafter, an Orthogonal Frequency Division Multiplexing (OFDM)numerology and a frame structure, which may be considered in the NRsystem, will be described.

A plurality of OFDM numerologies supported in the NR system may bedefined as in Table 1.

TABLE 1 μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal 5 480 Normal

Regarding a frame structure in the NR system, a size of various fieldsin the time domain is expressed as a multiple of a time unit ofT_(s)=1/(Δf_(max)·N_(f)). In this case, Δf_(max)=480·10³, andN_(f)=4096. DL and UL transmission is configured as a radio frame havinga section of T_(f)=(Δf_(max)N_(f)/100)·T_(s)=10 ms. The radio frame iscomposed of ten subframes each having a section ofT_(sf)=(Δf_(max)N_(f)/1000)·T_(s)=1 ms. In this case, there may be a setof UL frames and a set of DL frames.

FIG. 2 illustrates a relationship between a UL frame and a DL frame in awireless communication system to which a method proposed by the presentdisclosure may be implemented.

As illustrated in FIG. 2, a UL frame number I from a User Equipment (UE)needs to be transmitted T_(TA)=N_(TA)T_(s) before the start of acorresponding DL frame in the UE.

Regarding the numerology μ, slots are numbered in ascending order ofn_(s) ^(μ)∈{0, . . . , N_(subframe) ^(slots, μ)−1} in a subframe, and inascending order of n_(s,f) ^(μ)∈{0, . . . , N_(frame) ^(slots, μ)−1} ina radio frame. One slot is composed of continuous OFDM symbols ofN_(symb) ^(μ), and N_(symb) ^(μ) is determined depending on a numerologyin use and slot configuration. The start of slots n_(s) ^(μ) in asubframe is temporally aligned with the start of OFDM symbols n_(s)^(μ)N_(symb) ^(μ) in the same subframe.

Not all UEs are able to transmit and receive at the same time, and thismeans that not all OFDM symbols in a DL slot or an UL slot are availableto be used.

Table 2 shows the number of OFDM symbols per slot for a normal CP in thenumerology μ, and Table 3 shows the number of OFDM symbols per slot foran extended CP in the numerology μ.

TABLE 2 Slot configuration 0 1 μ N_(symb) ^(μ) N_(frame) ^(slots, μ)N_(subframe) ^(slots, μ) N_(symb) ^(μ) N_(frame) ^(slots, μ)N_(subframe) ^(slots, μ) 0 14 10 1 7 20 2 1 14 20 2 7 40 4 2 14 40 4 780 8 3 14 80 8 — — — 4 14 160 16 — — — 5 14 320 32 — — —

TABLE 3 Slot configuration 0 1 μ N_(symb) ^(μ) N_(frame) ^(slots, μ)N_(subframe) ^(slots, μ) N_(symb) ^(μ) N_(frame) ^(slots, μ)N_(subframe) ^(slots, μ) 0 12 10 1 6 20 2 1 12 20 2 6 40 4 2 12 40 4 680 8 3 12 80 8 — — — 4 12 160 16 — — — 5 12 320 32 — — —

NR Physical Resource

Regarding physical resources in the NR system, an antenna port, aresource grid, a resource element, a resource block, a carrier part,etc. may be considered.

Hereinafter, the above physical resources possible to be considered inthe NR system will be described in more detail.

First, regarding an antenna port, the antenna port is defined such thata channel over which a symbol on one antenna port is transmitted can beinferred from another channel over which a symbol on the same antennaport is transmitted. When large-scale properties of a channel receivedover which a symbol on one antenna port can be inferred from anotherchannel over which a symbol on another antenna port is transmitted, thetwo antenna ports may be in a QC/QCL (quasi co-located or quasico-location) relationship. Herein, the large-scale properties mayinclude at least one of delay spread, Doppler spread, Doppler shift,average gain, and average delay.

FIG. 3 illustrates an example of a resource grid supported in a wirelesscommunication system to which a method proposed by the presentdisclosure may be implemented.

Referring to FIG. 3, a resource grid is composed of N_(RB) ^(μ)N_(sc)^(RB) subcarriers in a frequency domain, each subframe composed of 14·2μOFDM symbols, but the present disclosure is not limited thereto.

In the NR system, a transmitted signal is described by one or moreresource grids, composed of N_(RB) ^(μ)N_(sc) ^(RB) subcarriers, and2^(μ)N_(symb) ^((μ)) OFDM symbols. Herein, N_(RB) ^(μ)≤N_(RB) ^(max, μ).The above N_(RB) ^(max, μ) indicates the maximum transmission bandwidth,and it may change not just between numerologies, but between UL and DL.

In this case, as illustrated in FIG. 3, one resource grid may beconfigured for the numerology μ and an antenna port p.

FIG. 4 illustrates examples of a resource grid per antenna port andnumerology to which a method proposed by the present specification isapplicable.

Each element of the resource grid for the numerology μ and the antennaport p is indicated as a resource element, and may be uniquelyidentified by an index pair (k,l). Herein, k=0, . . . , N_(RB)^(μ)N_(sc) ^(RB)−1 is an index in the frequency domain, and l=0, . . . ,2^(μ)N_(symb) ^((μ))−1 indicates a location of a symbol in a subframe.To indicate a resource element in a slot, the index pair (k,l) is used.Herein, l=0, . . . , N_(symb) ^(μ)−1.

The resource element (k,l) for the numerology μ and the antenna port pcorresponds to a complex value a_(k,l) ^((p)). When there is no risk ofconfusion or when a specific antenna port or numerology is specified,the indexes p and μ may be dropped and thereby the complex value maybecome a_(k,l) ^((p)) or a_(k,l) .

In addition, a physical resource block is defined as N_(sc) ^(RB)=12continuous subcarriers in the frequency domain. In the frequency domain,physical resource blocks may be numbered from 0 to N_(RB) ^(μ)−1. Atthis point, a relationship between the physical resource block numbern_(PRB) and the resource elements (k,l) may be given as in Equation 1.n _(PRB)=└ N _(sc) ^(RB) ┘  [Equation 1]

In addition, regarding a carrier part, a UE may be configured to receiveor transmit the carrier part using only a subset of a resource grid. Atthis point, a set of resource blocks which the UE is configured toreceive or transmit are numbered from 0 to N_(RB) ^(μ)−1 in thefrequency region.

Uplink Control Channel

Physical uplink control signaling should be able to carry at leasthybrid-ARQ acknowledgements, CSI reports (possibly including beamforminginformation), and scheduling requests.

At least two transmission methods are supported for an UL controlchannel supported in an NR system.

The UL control channel can be transmitted in short duration around lasttransmitted UL symbol(s) of a slot. In this case, the UL control channelis time-division-multiplexed and/or frequency-division-multiplexed withan UL data channel in a slot. For the UL control channel in shortduration, transmission over one symbol duration of a slot is supported.

Short uplink control information (UCI) and data arefrequency-division-multiplexed both within a UE and between UEs at leastfor the case where physical resource blocks (PRBs) for short UCI anddata do not overlap.

In order to support time division multiplexing (TDM) of a short PUCCHfrom different UEs in the same slot, a mechanism is supported to informthe UE of whether or not symbol(s) in a slot to transmit the short PUCCHis supported at least above 6 GHz.

At least following is supported for the PUCCH in 1-symbol duration: 1)UCI and a reference signal (RS) are multiplexed in a given OFDM symbolin a frequency division multiplexing (FDM) manner if an RS ismultiplexed, and 2) there is the same subcarrier spacing betweendownlink (DL)/uplink (UL) data and PUCCH in short-duration in the sameslot.

At least a PUCCH in short-duration spanning 2-symbol duration of a slotis supported. In this instance, there is the same subcarrier spacingbetween DL/UL data and the PUCCH in short-duration in the same slot.

At least semi-static configuration, in which a PUCCH resource of a givenUE within a slot. i.e., short PUCCHs of different UEs can betime-division multiplexed within a given duration in a slot, issupported.

The PUCCH resource includes a time domain, a frequency domain, and whenapplicable, a code domain.

The PUCCH in short-duration can span until an end of a slot from UEperspective. In this instance, no explicit gap symbol is necessary afterthe PUCCH in short-duration.

For a slot (i.e., DL-centric slot) having a short UL part, ‘short UCI’and data can be frequency-division multiplexed by one UE if data isscheduled on the short UL part.

The UL control channel can be transmitted in long duration over multipleUL symbols so as to improve coverage. In this case, the UL controlchannel is frequency-division-multiplexed with the UL data channelwithin a slot.

UCI carried by along duration UL control channel at least with a lowpeak to average power ratio (PAPR) design can be transmitted in one slotor multiple slots.

Transmission across multiple slots is allowed for a total duration (e.g.1 ms) for at least some cases.

In the case of the long duration UL control channel, the TDM between theRS and the UCI is supported for DFT-S-OFDM.

Along UL part of a slot can be used for transmission of PUCCH inlong-duration. That is, the PUCCH in long-duration is supported for botha UL-only slot and a slot having the variable number of symbolscomprised of a minimum of 4 symbols.

For at least 1 or 2 UCI bits, the UCI can be repeated within N slots(N>1), and the N slots may be adjacent or may not be adjacent in slotswhere PUCCH in long-duration is allowed.

Simultaneous transmission of PUSCH and PUCCH for at least the long PUCCHis supported. That is, uplink control on PUCCH resources is transmittedeven in the case of the presence of data. In addition to thesimultaneous PUCCH-PUSCH transmission, UCI on the PUSCH is supported.

Intra-TTI slot frequency-hopping is supported.

DFT-s-OFDM waveform is supported.

Transmit antenna diversity is supported.

Both the TDM and the FDM between the short duration PUCCH and the longduration PUCCH are supported for different UEs in at least one slot. Ina frequency domain, a PRB (or multiple PRBs) is a minimum resource unitsize for the UL control channel. If hopping is used, a frequencyresource and the hopping may not spread over a carrier bandwidth.Further, a UE-specific RS is used for NR-PUCCH transmission. A set ofPUCCH resources is configured by higher layer signaling, and a PUCCHresource within the configured set is indicated by downlink controlinformation (DCI).

As part of the DCI, timing between data reception and hybrid-ARQacknowledgement transmission should be able to be dynamically indicated(at least in combination with RRC). A combination of the semi-staticconfiguration and (for at least some types of UCI information) dynamicsignaling is used to determine the PUCCH resource for both ‘long andshort PUCCH formats’. Here, the PUCCH resource includes a time domain, afrequency domain, and when applicable, a code domain. The UCI on thePUSCH, i.e., using some of the scheduled resources for the UCI issupported in case of simultaneous transmission of UCI and data.

At least UL transmission of at least single HARQ-ACK bit is supported. Amechanism enabling the frequency diversity is supported. In case ofultra-reliable and low-latency communication (URLLC), a time intervalbetween scheduling request (SR) resources configured for a UE can beless than a slot.

Beam Management

In NR, beam management is defined as follows.

Beam management: a set of L1/L2 procedures to acquire and maintain a setof TRP(s) and/or UE beams that can be used for DL and ULtransmission/reception, which includes at least following aspects:

Beam determination: an operation for TRP(s) or UE to select its owntransmission/reception beam.

Beam measurement: an operation for TRP(s) or UE to measurecharacteristics of received beamformed signals.

Beam reporting: an operation for UE to report information of beamformedsignal based on beam measurement.

Beam sweeping: an operation of covering a spatial area using transmittedand/or received beams during a time interval in a predetermined way.

Also, the followings are defined as Tx/Rx beam correspondence at the TRPand the UE.

Tx/Rx beam correspondence at TRP holds if at least one of the followingsis satisfied.

The TRP is able to determine a TRP reception beam for the uplinkreception based on UE's downlink measurement on TRP's one or moretransmission beams.

The TRP is able to determine a TRP Tx beam for the downlink transmissionbased on TRP's uplink measurement on TRP's one or more Rx beams.

Tx/Rx beam correspondence at UE holds if at least one of the followingsis satisfied.

The UE is able to determine a UE Tx beam for the uplink transmissionbased on UE's downlink measurement on UE's one or more Rx beams.

The UE is able to determine a UE reception beam for the downlinkreception based on TRP's indication based on uplink measurement on UE'sone or more Tx beams.

Capability indication of UE beam correspondence related information toTRP is supported.

The following DL L1/L2 beam management procedures are supported withinone or multiple TRPs.

P-1: is used to enable UE measurement on different TRP Tx beams so as tosupport selection of TRP Tx beams/UE Rx beam(s).

In case of beamforming at the TRP, it generally includes intra/inter-TRPTx beam sweep from a set of different beams. For beamforming at the UE,it typically includes UE Rx beam sweep from a set of different beams.

P-2: is used to enable UE measurement on different TRP Tx beams tochange inter/intra-TRP Tx beam(s).

P-3: is used to enable UE measurement on the same TRP Tx beam to changeUE Rx beam in the case where the UE uses beamforming.

At least network triggered aperiodic reporting is supported under P-1,P-2, and P-3 related operations.

The UE measurement based on an RS for the beam management (at leastCSI-RS) is composed of K beams (where K is a total number of beams), andthe UE reports measurement results of N selected Tx beams, where N isnot necessarily fixed number. A procedure based on an RS for mobilitypurpose is not precluded. Reporting information at least includesmeasurement quantities for N beam(s) and information indicating N DLtransmission beam(s), if N<K. Specifically, for K′>1 non-zero power(NZP) CSI-RS resources of the UE, the UE can report N′ CRI (CSI-RSresource indicator).

The UE can be configured with the following higher layer parameters forbeam management.

N≥1 reporting settings, M≥1 resource settings

Links between reporting settings and resource settings are configured inthe agreed CSI measurement setting.

CSI-RS based P-1 and P-2 are supported with resource and reportingsettings.

P-3 can be supported with or without the reporting setting.

A reporting setting including at least the followings

Information Indicating Selected Beam

L1 measurement reporting

Time domain behavior (e.g. aperiodic operation, periodic operation, andsemi-persistent operation)

Frequency granularity if several frequency granularities are supported

A resource setting including at least the followings

Time domain behavior (e.g. aperiodic operation, periodic operation, andsemi-persistent operation)

RS type: at least NZP CSI-RS

At least one CSI-RS resource set. Each CSI-RS resource set includes K≥1CSI-RS resources (some parameters of K CSI-RS resources may be the same.For example, port number, time domain behavior, density andperiodicity).

Also, NR supports the following beam reporting considering L groups,where L>1.

Information Indicating at Least Group

Measurement quantity for N1 beam (supporting of L1 RSRP and CSI report(when CSI-RS is for CSI acquirement))

Information indicating N1 DL transmission beam, if applicable

The above-described group based beam reporting can be configured per UEbasis.

The above group based beam reporting can be turned off per UE basis(e.g. when L=1 or N1=1).

NR supports that the UE can trigger a mechanism recovering from abeamfailure.

A beam failure event occurs when the quality of beam pair link(s) of anassociated control channel is low enough (e.g. comparison with athreshold value, time-out of an associated timer). The mechanism torecover from the beam failure (or beam obstacle) is triggered when thebeam failure occurs.

A network explicitly configures to the UE with resources fortransmitting UL signals for recovery purpose. Configurations ofresources are supported where the base station is listening from all orsome directions (e.g. random access region).

The UL transmission/resources to report the beam failure can be locatedat the same time instance as PRACH (resources orthogonal to PRACHresources) or at a time instance (configurable for the UE) differentfrom the PRACH. The transmission of DL signal is supported for allowingthe UE to monitor beams for identifying new potential beams.

NR supports the beam management regardless of a beam-related indication.When the beam-related indication is provided, information pertaining toa UE-side beamforming/receiving procedure used for CSI-RS-basedmeasurement can be indicated to the UE through QCL.

As QCL parameters to support in NR, a spatial parameter for beamformingat a receiver will be added as well as parameters for delay, Doppler,average gain, etc. that have been used in a LTE system. The QCLparameters may include angle-of-arrival related parameters from UEreception beamforming perspective and/or angle-of-departure relatedparameters from base station reception beamforming perspective.

NR supports using the same beam or different beams on control channeland corresponding data channel transmissions.

For NR-PDCCH (physical downlink control channel) transmission supportingrobustness against beam pair link blocking, the UE can be configured tomonitor NR-PDCCH on M beam pair links simultaneously, where M≥1 and amaximum value of M may depend on at least UE capability.

The UE can be configured to monitor NR-PDCCH on different beam pairlink(s) in different NR-PDCCH OFDM symbols. Parameters related to UE Rxbeam setting for monitoring NR-PDCCH on multiple beam pair links areconfigured by higher layer signaling or MAC CE and/or considered in asearch space design.

At least, NR supports an indication of spatial QCL assumption between DLRS antenna port(s) and DL RS antenna port(s) for demodulation of DLcontrol channel. Candidate signaling methods for beam indication for aNR-PDCCH (i.e. configuration method to monitor NR-PDCCH) are MAC CEsignaling, RRC signaling, DCI signaling, specification-transparentand/or implicit method, and combination of these signaling methods.

For reception of unicast DL data channel, NR supports an indication ofspatial QCL assumption between a DL RS antenna port and a DMRS antennaport of DL data channel.

Information indicating an RS antenna port is indicated via DCI (downlinkgrant). The information indicates the RS antenna port which is QCL-edwith the DMRS antenna port. A different set of DMRS antenna ports forthe DL data channel can be indicated as QCL with a different set of RSantenna ports.

Hybrid Beamforming

Existing beamforming technology using multiple antennas may beclassified into an analog beamforming scheme and a digital beamformingscheme according to a location to which beamforming weightvector/precoding vector is applied.

The analog beamforming scheme is a beamforming technique applied to aninitial multi-antenna structure. The analog beamforming scheme may meana beamforming technique which branches analog signals subjected todigital signal processing into multiple paths and then appliesphase-shift (PS) and power-amplifier (PA) configurations for each path.

For analog beamforming, a structure in which an analog signal derivedfrom a single digital signal is processed by the PA and the PS connectedto each antenna is required. In other words, in an analog stage, acomplex weight is processed by the PA and the PS.

FIG. 5 illustrates an example of a block diagram of a transmittercomposed of an analog beamformer and an RF chain. FIG. 5 is merely forconvenience of explanation and does not limit the scope of the presentdisclosure.

In FIG. 5, the RF chain means a processing block for converting abaseband (BB) signal into an analog signal. The analog beamformingscheme determines beam accuracy according to characteristics of elementsof the PA and PS and may be suitable for narrowband transmission due tocontrol characteristics of the elements.

Further, since the analog beamforming scheme is configured with ahardware structure in which it is difficult to implement multi-streamtransmission, a multiplexing gain for transfer rate enhancement isrelatively small. In addition, in this case, beamforming per UE based onorthogonal resource allocation may not be easy.

On the contrary, in the case of digital beamforming scheme, beamformingis performed in a digital stage using a baseband (BB) process in orderto maximize diversity and multiplexing gain in a MIMO environment.

FIG. 6 illustrates an example of a block diagram of a transmittercomposed of a digital beamformer and an RF chain. FIG. 6 is merely forconvenience of explanation and does not limit the scope of the presentdisclosure.

In FIG. 6, beamforming can be performed as precoding is performed in theBB process. Here, the RF chain includes a PA. This is because a complexweight derived for beamforming is directly applied to transmission datain the case of digital beamforming scheme.

Furthermore, since different beamforming can be performed per UE, it ispossible to simultaneously support multi-user beamforming. Besides,since independent beamforming can be performed per UE to whichorthogonal resources are assigned, scheduling flexibility can beimproved and thus a transmitter operation suitable for the systempurpose can be performed. In addition, if a technology such as MIMO-OFDMis applied in an environment supporting wideband transmission,independent beamforming can be performed per subcarrier.

Accordingly, the digital beamforming scheme can maximize a maximumtransfer rate of a single UE (or user) based on system capacityenhancement and enhanced beam gain. On the basis of the above-describedproperties, digital beamforming based MIMO scheme has been introduced toexisting 3G/4G (e.g. LTE(-A)) system.

In the NR system, a massive MIMO environment in which the number oftransmit/receive antennas greatly increases may be considered. Incellular communication, a maximum number of transmit/receive antennasapplied to an MIMO environment is assumed to be 8. However, as themassive MIMO environment is considered, the number of transmit/receiveantennas may increase to above tens or hundreds.

If the aforementioned digital beamforming scheme is applied in themassive MIMO environment, a transmitter needs to perform signalprocessing on hundreds of antennas through a BB process for digitalsignal processing. Hence, signal processing complexity may significantlyincrease, and complexity of hardware implementation may remarkablyincrease because as many RF chains as the number of antennas arerequired.

Furthermore, the transmitter needs to perform independent channelestimation for all the antennas. In addition, in case of an FDD system,since the transmitter requires feedback information about a massive MIMOchannel composed of all antennas, pilot and/or feedback overhead mayconsiderably increase.

On the other hand, when the aforementioned analog beamforming scheme isapplied in the massive MIMO environment, hardware complexity of thetransmitter is relatively low.

However, an increase degree of a performance using multiple antennas isvery low, and flexibility of resource allocation may decrease. Inparticular, it is difficult to control beams per frequency in thewideband transmission.

Accordingly, instead of exclusively selecting only one of the analogbeamforming scheme and the digital beamforming scheme in the massiveMIMO environment, there is a need for a hybrid transmitter configurationscheme in which an analog beamforming structure and a digitalbeamforming structure are combined.

Analog Beam Scanning

In general, analog beamforming may be used in a pure analog beamformingtransmitter/receiver and a hybrid beamforming transmitter/receiver. Inthis instance, analog beam scanning can perform estimation for one beamat the same time. Thus, a beam training time required for the beamscanning is proportional to the total number of candidate beams.

As described above, the analog beamforming necessarily requires a beamscanning process in a time domain for beam estimation of thetransmitter/receiver. In this instance, an estimation time T_(s) for allof transmit and receive beams may be represented by the followingEquation 2.T _(S) =t _(s)×(K _(T) ×K _(R))  [Equation 2]

In Equation 2, ts denotes time required to scan one beam, K_(T) denotesthe number of transmit beams, and K_(R) denotes the number of receivebeams.

FIG. 7 illustrates an example of an analog beam scanning schemeaccording to various embodiments of the present disclosure. FIG. 7 ismerely for convenience of explanation and does not limit the scope ofthe present disclosure.

In FIG. 7, it is assumed that the total number K_(T) of transmit beamsis L, and the total number K_(R) of receive beams is 1. In this case,since the total number of candidate beams is L, L time intervals arerequired in the time domain.

In other words, since only the estimation of one beam can be performedin a single time interval for analog beam estimation, L time intervalsare required to estimate all of L beams P1 to PL as shown in FIG. 7. TheUE feeds back, to the base station, an identifier (ID) of a beam with ahighest signal strength after an analog beam estimation procedure isended. Namely, as the number of individual beams increases according toan increase in the number of transmit/receive antennas, a longertraining time may be required.

Because the analog beamforming changes a magnitude and a phase angle ofa continuous waveform of the time domain after a digital-to-analogconverter (DAC), a training interval for an individual beam needs to besecured for the analog beamforming, unlike the digital beamforming.Thus, as a length of the training interval increases, efficiency of thesystem may decrease (i.e., a loss of the system may increase).

Channel State Information (CSI) Feedback

In most cellular systems including the LTE system, a UE receives a pilotsignal (reference signal) for channel estimation from a base station,calculates channel state information (CSI), and reports the calculatedCSI to the base station.

The base station transmits a data signal based on the CSI fed back fromthe UE.

In the LTE system, the CSI fed back by the UE includes channel qualityinformation (CQI), a precoding matrix index (PMI), and a rank indicator(RI).

CQI feedback is radio channel quality information provided to the basestation for the purpose (link adaptation purpose) of providing a guideas to which modulation and coding scheme (MCS) the base station applieswhen transmitting data.

If radio quality between the base station and the UE is high, the UE mayfeedback a high CQI value to the base station, and the base station maytransmit data using a relatively high modulation order and a low channelcoding rate. On the contrary, if radio quality between the base stationand the UE is low, the UE may feedback a low CQI value to the basestation, and the base station may transmit data using a relatively lowmodulation order and a high channel coding rate.

PMI feedback is preferred precoding matrix information provided to thebase station for the purpose of providing a guide as to which MIMOprecoding scheme the base station applies when installing multipleantennas.

The UE estimates a downlink MIMO channel between the base station andthe UE from the pilot signal and recommends which MIMO precoding schemeis applied to the base station through the PMI feedback.

In the LTE system, only linear MIMO precoding that is representable inthe form of a matrix is considered in PMI configuration.

The base station and the UE share a codebook composed of multipleprecoding matrices, and each MIMO precoding matrix within the codebookhas a unique index.

Accordingly, the UE feeds back an index corresponding to a mostpreferred MIMO precoding matrix within the codebook as a PMI to therebyminimize an amount of feedback information of the UE.

A PMI value needs not be necessarily configured as one index. Forexample, in the LTE system, when the number of transmit antenna ports is8, a final 8tx MIMO precoding matrix may be derived by combining twoindices (i.e., a first PMI and a second PMI).

RI feedback is information about the number of preferred transmissionlayers provided to the base station for the purpose of providing a guideto the number of transmission layers preferred by the UE when the UE andthe base station enable multi-layer transmission through spatialmultiplexing by installing multiple antennas.

The RI has a very close relationship with the PMI. This is because thebase station needs to know which precoding will be applied to each layeraccording to the number of transmission layers.

In PMI/RI feedback configuration, a method of configuring a PMI codebookon the basis of single layer transmission, defining a PMI per layer andfeeding back the PMI may be considered. However, the method has adisadvantage in that an amount of PMI/RI feedback information greatlyincreases due to an increase in the number of transmission layers.

Accordingly, in the LTE system, a PMI codebook has been defined pernumber of transmission layers. That is, N Nt×R matrices are defined in acodebook for R-layer transmission, where R is the number of layers, Ntis the number of transmit antenna ports, and N is the size of thecodebook.

Accordingly, in the LTE system, the size of a PMI codebook is definedirrespective of the number of transmission layers. Since the number R oftransmission layers is eventually equal to a rank value of a precodingmatrix (Nt×R matrix) as the PMI/RI is defined with such a structure, aterm of rank indicator (RI) has been used.

The PMI/RI described in the present specification is not limited to meanan index value and a rank value of a precoding matrix represented asNt×R matrix, like PMI/RI in the LTE system.

The PMI described in the present specification indicates information ofa preferred MIMO precoder among MIMO precoders applicable to atransmitter, and a form of the precoder is not limited to only a linearprecoder that can be represented as a matrix as in the LTE system.Further, the RI described in the present specification is interpreted ina broader sense than RI in LTE and includes all of feedback informationindicating the number of preferred transmission layers.

The CSI may be obtained in all of system frequency domains and may bealso obtained in some frequency domains. In particular, it may be usefulfor a wideband system to obtain CSI for some preferred frequency domains(e.g. subband) per UE and feedback the CSI.

In the LTE system, CSI feedback is performed on an uplink channel. Ingeneral, periodic CSI feedback is performed on a physical uplink controlchannel (PUCCH), and aperiodic CSI feedback is performed on a physicaluplink shared channel (PUSCH) which is an uplink data channel.

The aperiodic CSI feedback is temporarily performed only when the basestation desires CSI feedback information, and the base station triggersthe CSI feedback on a downlink control channel such as PDCCH/ePDCCH.

When the CSI feedback has been triggered in the LTE system, whichinformation the UE should feedback is classified into PUSCH CSIreporting modes as shown in FIG. 8. The UE is previously informed ofwhich PUSCH CSI reporting mode the UE should operate in through a higherlayer message.

FIG. 8 illustrates an example of a PUSCH CSI reporting mode.

The PUCCH CSI reporting mode is also defined for the periodic CSIfeedback on the PUCCH.

FIG. 9 illustrates an example of a PUCCH CSI reporting mode.

In the case of PUCCH, since an amount (i.e., a payload size) of datawhich can be transmitted at once is less than that in the PUSCH, it isdifficult to transmit CSI, that needs to be transmitted, at once.

Accordingly, a time at which CQI and PMI are transmitted and a time atwhich RI is transmitted are different from each other according to eachCSI reporting mode. For example, in reporting mode 1-0, only RI istransmitted at a specific PUCCH transmission time, and wideband CQI istransmitted at another PUCCH transmission time. A PUCCH reporting typeis defined according to kinds of CSI configured at the specific PUCCHtransmission time. For example, a reporting type of transmitting onlythe RI corresponds to type 3, and a reporting type of transmitting onlythe wideband CQI corresponds to type 4. A feedback periodicity and anoffset value of the RI and a feedback periodicity and an offset value ofCQI/PMI are configured to the UE through higher layer message.

The above CSI feedback information is included in uplink controlinformation (UCI).

Reference Signals in LTE

In the LTE system, the purpose of a pilot signal or a reference signal(RS) may be roughly divided as follows.

Measurement RS: pilot for channel state measurement

CSI measurement/reporting purpose (short term measurement): purpose oflink adaptation, rank adaptation, closed loop MIMO precoding, etc.

Long term measurement/reporting purpose: purpose of handover, cellselection/reselection, etc.

Demodulation RS: pilot for physical channel reception

Positioning RS: pilot for UE location estimation

MBSFN RS: pilot for multi-cast/broadcast service

In LTE Rel-8, a cell-specific RS (CRS) has been used for measurement(purpose 1 A/B) and demodulation (purpose 2) for most of downlinkphysical channels. However, in order to solve RS overhead problem due toan increase in the number of antennas, from LTE Advanced (Rel-10), aCSI-RS is used dedicatedly for CSI measurement (purpose 1A), and aUE-specific RS is used dedicatedly for the reception (purpose 2) ofdownlink data channel (PDSCH).

The CSI-RS is an RS designed dedicatedly for the CSI measurement andfeedback and is characterized by having an RS overhead much lower thanthe CRS. The CRS supports up to 4 antenna ports, whereas the CSI-RS isdesigned to support up to 8 antenna ports. The UE-specific RS isdesigned dedicatedly for demodulation of a data channel and, unlike theCRS, is characterized in that it is an RS (precoded RS) in which a MIMOprecoding scheme applied when data is transmitted to the correspondingUE is equally applied to a pilot signal.

Accordingly, as many UE-specific RSs as the number of antenna ports donot need to be transmitted as in the CRS and the CSI-RS, and as manyUE-specific RSs as the number of transmission layers (i.e., transmissionranks) are transmitted.

Further, since the UE-specific RS is transmitted for the data channelreception purpose of the corresponding UE in the same resource region asa data channel resource region allocated to each UE through a schedulerof the base station, it is characterized to be UE-specific.

In addition, since the CRS is always transmitted in the same patternwithin a system bandwidth so that all of UEs within the cell can use theCRS for the purposes of measurement and demodulation, it iscell-specific.

In LTE uplink, a sounding RS (SRS) has been designed as a measurementRS, and a demodulation RS (DMRS) for an uplink data channel (PUSCH) anda DMRS for an uplink control channel (PUCCH) for ACK/NACK and CSIfeedback have been individually designed.

Self-Contained Subframe Structure

A time division duplexing (TDD) structure considered in the NR system isa structure in which both uplink (UL) and downlink (DL) are processed inone subframe. The structure is to minimize a latency of datatransmission in a TDD system and is referred to as a self-containedsubframe structure.

FIG. 10 illustrates an example of a self-contained subframe structure towhich a method proposed by the present specification is applicable. FIG.10 is merely for convenience of explanation and does not limit the scopeof the present disclosure.

Referring to FIG. 10, as in legacy LTE, it is assumed that one subframeis composed of 14 orthogonal frequency division multiplexing (OFDM)symbols.

In FIG. 10, a region 1002 means a downlink control region, and a region1004 means an uplink control region. Further, regions (i.e., regionswithout separate indication) other than the region 1002 and the region1004 may be used for transmission of downlink data or uplink data.

Namely, uplink control information and downlink control information aretransmitted in one self-contained subframe. On the other hand, in caseof data, uplink data or downlink data is transmitted in oneself-contained subframe.

When the structure shown in FIG. 10 is used, downlink transmission anduplink transmission are sequentially performed in one self-containedsubframe, and downlink data transmission and uplink ACK/NACK receptioncan be performed.

As a result, if an error occurs in the data transmission, time requireduntil retransmission of data can be reduced. Hence, the latency relatedto data transfer can be minimized.

In the self-contained subframe structure shown in FIG. 10, a basestation (e.g. eNodeB, eNB, gNB) and/or a user equipment (UE) (e.g.terminal) require a time gap for a process for converting a transmissionmode into a reception mode or a process for converting a reception modeinto a transmission mode. Regarding the time gap, when uplinktransmission is performed after downlink transmission in theself-contained subframe, some OFDM symbol(s) may be configured as aguard period (GP).

3GPP NR will support the following three time-domain behaviors relatedto CSI reporting. Similarly, reporting for (analog) beam management canalso support some or all of the following three time-domain behaviors.

Aperiodic CSI Reporting

CSI reporting is performed only in triggering

Semi-Persistent CSI Reporting

If activation, CSI reporting starts (on specific periodicity), and ifdeactivation, the CSI reporting is discontinued.

Periodic CSI Reporting

Periodic CSI reporting performs CSI reporting with RRC configuredperiodicity and slot offset.

A downlink reference signal (DL RS) for channel measurement in CSIacquisition will also support the following three time-domain behaviors.Similarly, a DL RS for beam management can also support some or all ofthe following three time-domain behaviors.

The DL RS for beam management will basically include a CSI-RS, and otherdownlink signals may be utilized.

Examples of the other downlink signals may use a mobility RS, a beam RS,a synchronization signal (SS), and a SS block, DL DMRSs (e.g. PBCH DMRS,PDCCH DMRS).

Aperiodic CSI-RS

CSI-RS measurement is performed only in triggering

Semi-Persistent CSI-RS

If activation, CSI-RS measurement starts (on specific periodicity), andif deactivation, the CSI-RS measurement is discontinued.

Periodic CSI-RS

Periodic CSI-RS performs CSI-RS measurement with RRC configuredperiodicity and slot offset.

Further, in CSI acquisition, a zero-power (ZP) CSI-RS based interferencemeasurement method which has been utilized in LTE will be supported toan interference measurement resource (IMR) which is designated to the UEby the base station. In addition, at least one of a non-zero-power (NZP)CSI-RS based interference measurement method or a DMRS basedinterference measurement method will be supported.

In particular, in the LTE system, ZP CSI-RS based IMR has beenconfigured as semi-static (via RRC signaling), whereas a dynamicallyconfigured method will be supported in NR. Also, the following threetime-domain behaviors will be supported.

Aperiodic IMR with ZP CSI-RS

Semi-persistent IMR with ZP CSI-RS

Periodic IMR with ZP CSI-RS

Accordingly, channel estimation, interference estimation, and reportingconfiguring CSI measurement and reporting may use combinations of thefollowing various time domain behaviors.

Hereinafter, aperiodic is simply represented as AP, semi-persistent issimply represented as SP, and periodic is simply represented as PR forconvenience of explanation.

Example 1) AP CSI reporting with AP/SP/PR NZP CSI-RS for channelmeasurement and AP/SP/PR ZP CSI-RS for interference estimation.

Example 2) SP CSI reporting with AP/SP/PR NZP CSI-RS for channelmeasurement and AP/SP/PR ZP CSI-RS for interference estimation.

Example 3) PR CSI reporting with PR NZP CSI-RS for channel measurementand PR ZP CSI-RS for interference estimation.

In the above examples, it is assumed that AP RS/IMR is used only in APreporting, SP RS/IMR is used only in AP reporting or SP reporting, andPR RS/IMR is used in all reportings. However, they are not limitedthereto.

Further, both RS and IMR may be included in resource setting, and theirpurpose, i.e., channel estimation or interference estimation may beindicated through configuration for each link in measurement setting.

In New Rat (NR), as the PUCCH, a short PUCCH and a long PUCCH areconsidered.

The short PUCCH may be transmitted by using one or two OFDM symbols asthe time domain and transmitted by using one or more physical resourceblocks (PRBs) as the frequency domain.

Table 4 below is a table showing one example of the PUCCH format definedin the NR.

Table 4

TABLE 4 PUCCH format Length in OFDM symbols 0 1-2 1 4-14 2 1-2 3 4-14 44-14

In Table 4, PUCCH formats 0 and 2 may be the short PUCCH and PUCCHformats 1, 3, and 4 may be the long PUCCH. Next, the long PUCCH may betransmitted by using 4 to 12 OFDM symbols in the time domain andtransmitted by using one or more physical resource blocks (PRBs) in thefrequency domain.

The short PUCCH may be primarily used for the purpose of feedback offast acknowledge (ACK) or non-acknowledge (NACK) for downlink (DL) datain the self-contained slot structure.

In addition, the long PUCCH may be used for the purpose of feedback ofthe ACK/NACK and the CSI by occupying a predetermined resource for eachUE similarly to the PUCCH of the LTE.

The minimum number of symbols of the long PUCCH is 4.

The reason is that various slot structures or slot formats in the NR areconsidered.

The slot defined in the NR will be simply described.

For subcarrier spacing configuration μ, slots are numbered with an orderin which the subcarrier spacing configuration μ increases, i.e., n_(s)^(μ)∈{0, . . . , N_(slot) ^(subframe, μ)−1} and numbered with an orderin which the subcarrier spacing configuration μ increases, i.e., n_(s)^(μ)∈{0, . . . , N_(slot) ^(subframe, μ)−1} in one (radio) frame.

For N_(symb) ^(slot), there are contiguous OFDM symbols N_(symb) ^(slot)in a slot which depends on the cyclic prefix.

The start of a slot n_(s) ^(μ) in the subframe and the start of an OFDMsymbol n_(s) ^(μ)N_(symb) ^(slot) in the same subframe are aligned witheach other in the time.

In the slot, the OFDM symbols may be classified into ‘downlink(D)’,‘flexible(X)’, or ‘uplink(U)’.

In a downlink slot, the UE may assume that the downlink transmissionoccurs only in ‘downlink’ or in the ‘flexible’ symbol.

In an uplink slot, the UE may assume that the uplink transmission occursonly in ‘uplink’ or in the ‘flexible’ symbols.

For reference, in the NR, the number of OFDM symbols included in oneslot may be 14 or 7.

Further, the slot structure may include various structures including aDL dominant structure (e.g., the PDCCH, the PDSCH, and the short PUCCHcoexist in the slot), a UL dominant structure (e.g., the PUCCH and thePUSCH coexist in the slot), and the like in addition to the downlink(DL) and the uplink (UL).

Further, a plurality of PUCCH formats may be defined in the short PUCCHand the long PUCCH (e.g., according to the maximum number of UEs whichmay be multiplexed or a channel coding scheme) and the size of thepayload which may be transmitted may be changed for each PUCCH format.

As mentioned above, the LTE(-A) system supports aperiodic CSI reportingand periodic CSI reporting and the CSI reporting is performed througheach of the PUSCH and the PUCCH.

Semi-persistent CSI reporting corresponds to a CSI reporting schemewhich is not supported in the LTE(-A) system.

Accordingly, the present disclosure provides a method indicating throughwhich uplink (UL) resource the CSI reporting is to be performed when thesemi-persistent (SP) CSI reporting is supported.

Semi-Persistent CSI Reporting on PUSCH

First, a method for performing the semi-persistent CSI reporting on thePUSCH will be described.

Such a method is characterized in that the UE is operated by linkingsemi-persistent PUSCH resource allocation information (similar tosemi-persistent scheduling (SPS) in the LTE system) with CSI reportingactivation.

That is, when the UE receives a CSI reporting activation message, the UEstarts CSI reporting to the eNB through the designated PUSCH resource inadvance or through SPS information transferred together with the CSIreporting activation message.

The CSI reporting activation may be indicated through an L1 (e.g., DCI)message or an L2 (e.g., MAC CE) message.

In addition, the SPS information may be transferred as L1 (e.g., DCI),L2 (e.g., MAC CE), or L3 (e.g., RRC) control information.

Further, the SPS information may be constituted by a temporalcharacteristic (e.g., a period or a slot offset) of the PUSCH resource,a frequency characteristic (e.g., PRB indexes), a code characteristic(e.g., sequence), and/or a spatial characteristic (e.g., DMRS port).

Some or all of the SPS information may be configured or designatedearlier than a CSI reporting activation instance (by L1 signaling, L2signaling, or L3 signaling).

When the SPS information is configured or designated earlier than theCSI reporting activation, the UE may start the CSI reporting through apredesignated SPS resource simultaneously with receiving the CSIreporting activation message.

That is, the CSI reporting activation message may indicate preconfiguredPUSCH activation.

When resource information for the SPS is preconfigured by the L2 or L3signaling, the resource information for the SPS may include period andslot/subframe offset information which is time resource informationtogether in addition to resource allocation (RA) information which isfrequency resource scheduling information.

Further, the frequency resource information may additionally includePUSCH hopping pattern information depending on a reporting instance.

The SPS information (e.g., RA) may be designated simultaneously with theCSI reporting activation instance, and when (1) the CSI reportingactivation is indicated by L1 (DCI), the SPS information may also beindicted by L1 and when (2) the CSI reporting activation is indicated byL2 (MAC CE), the SPS information may also be indicated by L2.

In the LTE system, SPS activation/release information for the PUSCH istransferred to the UE by using RNTI (i.e., SPS-C-RNTI) different fromRNTI (i.e., C-RNTI) for transferring general one shot DL/UL schedulinginformation to be configured to be distinguished in a PUCCH decodingstep.

In transferring SP reporting activation/deactivation information,whether RNTI (e.g., C-RNTI in LTE) for one shot scheduling is used,whether RNTI (e.g., SPS-C-RNTI in LTE) for PUSCH SPS is used, or amethod for assigning separate RNTI may be considered.

When being commonly used with RNTI (e.g., SPS-C-RNTI) for the PUSCH SPSin transferring the SP reporting activation/deactivation information,whether the UL grant is used for the PUSCH SPS, whether the UL grant isused for SP CSI reporting, (or whether the UL grant is used for both thePUSCH SPS and the SP CSI reporting) may be indicated by a 1 (or 2)-bitfield.

When the above-described contents are briefly summarized again, thesemi-persistent CSI reporting through the PUSCH is supported in the NR.In addition, the SP-CSI through the PUSCH is activated/deactivated bythe DCI.

In the method proposed by the present disclosure, RNTI is used which isseparated from C-RNTI for the SPS PUSCH for the DCI for indication ofactivation or deactivation of the SP-CSI through the PUSCH.

One example of the separate RNTI may be expressed by SP-CSI-RNTI.

That is, in the NR system, when both a VoTP service and SP-CSI reportingare used, it may be preferable to use the separate RNTI for each use.

The reason is that using the separate RNTI may reduce a misdetectionprobability for the DCI of the UE and add a valid bit to the DCI.

Further, the SP CSI reporting through the PUSCH is different from SPSscheduling in LTE used for the purpose of the VoP service in that the SPCSI reporting may be used for the purpose of controlling interferencewith a neighboring cell.

In addition, SP CSI transmission through the PUSCH is different from SPSscheduling that does not perform UL transmission when there is no datumto be transmitted in that the CSI is continuously transmitted orreported in the corresponding period with a predetermined period.

Additionally, a method for using RNTI for SP CSI activation/deactivation(release) commonly with RNTI (SPS C-RNTI) for the PUSCH SPS will bedescribed in more detail.

For the purpose of configuring two bits or fields in the transmitted DCIby using the RNTI (SPS C-RNTI) (for the purposes of the VoIP service andthe SP CSI reporting) and 1 bit (or one field) may be configured for thepurpose of indicating activation or release (or deactivation) for theSPS PUSCH (for carrying UL-SCH for the purpose of the VoIP service) andthe other 1 bit (or one field) may be configured for the purpose ofindicating activation or release for the SPS PUSCH for transmitting aCSI report.

Therefore, activation or release (or deactivation) may be indicated foronly one or both of the two SPS PUSCHs by using one UL grant.

In addition, when a method for performing the SP-CSI reporting issupported by using both (one shot) PUSCH and PUCCH to be describedbelow, CSI reporting triggering (or activation) may be indicated byC-RNTI for allocating one shot PUSCH.

Therefore, a CSI reporting scheme using a multi-shot (SPS) PUSCH throughthe RNTI or a scheme of performing the CSI reporting by using the PUCCHtogether with one shot PUSCH may be configured to be implicitlydistinguished.

The PUSCH SPS may be utilized even for always UL data transmission suchas the VoP service as in the LTE system in addition to the purpose ofthe SP CSI reporting.

On such a viewpoint, the allocated PUSCH SPS may be utilized for boththe SP CSI reporting and the UL data transmission.

In this case, when a data buffer is empty at the CSI reporting instance,only the CSI may be transmitted through the SPS CSI PUSCH and whenanother UL grant does not exist while there is the data, datatransmission to the SPS CSI PUSCH may be performed.

In this case, whether the data and the CSI are simultaneouslytransmitted may be indicated (by an independent field) in the CSI report(payload).

Alternatively, the data and CSI reporting information may bedistinguished by different time, frequencies, codes, and/or spatialresources in the allocated SPS PUSCH resource.

For example, the data and the CSI reporting information may bedistinguished through a DMRS sequence, a DMRS port(s), a scramblingsequence, etc.

Semi-Persistent CSI Reporting on PUCCH

Next, a method for performing the SP CSI reporting through the PUCCHwill be described.

That is, the corresponding method refers to a method for turning on oroff the CSI reporting to a (PUCCH resource selecting and selected) PUCCHin CSI reporting activation for one or a plurality of PUCCH resourceswhich is RRC-configured.

In this case, information for designating whether to perform the CSIreporting by using a specific PUCCH resource may be transmitted togetherwith the CSI reporting activation message or in advance.

The PUCCH resource may include a time, a frequency, a code (sequence),and/or a spatial resource of the PUCCH.

The spatial resource may be, for example, a PUCCH DMRS port indicator,etc.

A PUCCH resource release operation may be defined together with orseparately from the CSI reporting deactivation.

For example, an operation may be defined in which a plurality of PUCCHresources which is configured by the RRC is automatically reconfiguredby releasing a specific PUCCH resource.

The PUCCH resource release indication may be signaled together with orseparately from a reporting deactivation indication.

When the PUCCH resource release indication is signaled separately fromthe CSI reporting deactivation indication, the CSI reporting isdeactivated, but when there is a possibility that the CSI reporting willbe re-activated through the same PUCCH resource, the PUCCH resourcerelease may not be indicated.

The semi-persistent reporting using the PUCCH may be limitedly appliedto a specific PUCCH type (e.g., long PUCCH) or a specific PUCCHconfiguration (short PUCCH or long PUCCH, and specific PUCCH format(s)which are more than X symbols and/or Y PRBs) by considering a UCIpayload size.

Semi-Persistent CSI Reporting on PUCCH and PUSCH

Next, an SP-CSI reporting method through the PUCCH and the PUSCHmentioned for a moment will be described in detail.

That is, the corresponding method refers to a scheme of supporting theSP CSI reporting by using both the PUSCH and the PUCCH.

For example, when the eNB transmits UL resource allocation informationto the UE together with the CSI reporting activation message (which mayinclude PUCCH resource selection information), the UE may perform firstCSI reporting through the allocated PUSCH resource and then the CSIreporting may be performed through the configured (or selected) PUCCHresource.

As another example, when the allocated SPS PUSCH resource does not existany longer while which is allocated while the UE performs thesemi-persistent CSI reporting through the SPS PUSCH and the UE does notreceive the CSI reporting deactivation from the eNB or when theallocated SPS PUSCH resource collides with or overlaps with a moreimportant (UL or DL) resource (e.g., PUSCH with mini-slot (for PUSCH forURLLC), PUCCH), the UE may perform the CSI reporting to the PUCCHinstead of the SPS PUSCH in the corresponding slot or collision region.

Further, when both the PUSCH and the PUCCH are used for the SP CSIreporting, high resolution CSI may be reported through the PUSCH and lowresolution may be reported to the PUCCH.

Here, the SP CSI reporting through the PUCCH may be configured to havedependency on the CSI information reported through the PUSCH byconsidering a limit of a PUCCH payload size.

Alternatively, when the SP CSI reporting is performed by using both thePUSCH and the PUCCH, the entire CSI (i.e., the RI, the PMI, the CQI, andtogether with the CRI as necessary) may be reported through the PUSCHand some CSI (e.g., PMI only, CQI only, or PMI and CQI only) may bereported to the PUCCH.

Similarly, the SP CSI reporting through the PUCCH may be configured tohave dependency on the CSI information reported through the PUSCH byconsidering the limit of the PUCCH payload size.

For example, a PMI codebook subset may be determined which becomes areference in subsequent PUCCH reporting based on the reported PMI valueat the time of reporting the CSI to the PUSCH.

That is, candidate PMIs to be reported to the PUCCH are limited based onthe PMI reported in the PUSCH according to a specific rule to reduce thePMI payload size at the time of reporting the PUCCH.

Here, the ‘specific rule’ may be a rule promised between the eNB and theUE or may allow the eNB to follow a scheme of directly configuring ordesignating a codebook subset without the specific rule.

For example, only a W2 value may be transmitted at the time of thesubsequent PUCCH CSI reporting while maintaining that a W1 valueincluded in the PUSCH CSI reporting is maintained.

When a plurality of W2s should be transmitted for each subband,respective W2s may be sequentially transmitted through contiguous PUCCHtransmission.

Similarly, a differential CQI value (a difference value compared with areference CQI) may be transmitted at the time of reporting the PUCCHbased on the CQI value reported to the PUSCH.

The RI value is also similarly configured to transmit the differentialRI value in the PUCCH based on the RI value reported to the PUSCH toreduce the payload size of the PUCCH.

The eNB may also designate a CSI parameter to be updated at eachreporting instance in the PUCCH based CSI transmission.

Alternatively, the UE may directly determine the CSI parameter to beupdated and report which CSI parameter is updated together with the CSI.

In this case, since update of the CRI, the RI, etc., influences theentire CSI, the update may not be appropriate as partial CSI update.

When the UE updates partial CSI through the PUCCH, CSI (e.g., CRI, RI)other than partial CSI update target may be calculated by assuming avalue of most recently reported PUSCH CSI.

For example, when the CQI and the PMI (e.g., W2 only) are updated, theCRI, the RI, and the W1 are calculated by assuming a value reportedthrough a most recent PUSCH.

In such a method, it is assumed that both the PUCCH and the PUSCH areused for one semi-persistent CSI reporting, but such a method may beextensively applied as a scheme of using both the PUCCH and the PUSCHfor a plurality of independent aperiodic CSI reporting/SP CSI reporting.

For example, in the case of a UE which completes transmission of highresolution CSI information to the PUSCH (or contiguous PUCCH), the eNBmay indicate PUCCH based aperiodic CSI/SP CSI reporting through aseparate indication.

In this case, the CSI value transmitted through the PUCCH has adependency on the CSI value reported in the PUSCH as described above toachieve efficient CSI reporting even with a small payload size.

In this case, at the time of indicating the PUCCH based CSI reporting,PUSCH CSI reporting which becomes the reference may be dynamicallyindicated through the L1 or L2 signaling or configured semi-staticallythrough L3 (RRC) signaling.

When the PUSCH CSI reporting which becomes the reference is configuredsemi-statically through the L3 signaling, PUCCH based CSI reporting andPUSCH based CSI reporting may be included in one reporting setting oreach included in independent reporting setting.

In this case, in order to notify that there is dependency in calculatingand reporting the CSI, the eNB may notify to the UE that there is anassociation between reporting settings or between links included inmeasurement setting through a separate indicator.

When an error occurs in PUSCH decoding with respect to an operation ofupdating the CSI with the PUCCH after first transmitting the CSI reportto the PUSCH, there may be a problem in that subsequent PUCCH based CSIreporting information may also be understood (or interpreted)differently.

In order to solve the problem, when an operation is defined in which theeNB sends ACK/NACK to initial PUSCH transmission (e.g., # n-th slot)(e.g., #(n+k) slot), if the ACK is received by the UE at an instant of#(n+k), the UE may continuously perform PUCCH transmission which isnormally proposed.

However, when NACK is received by the UE at the instance of #(n+k), theUE may perform retransmission with respect to the initial PUSCHtransmission according to a previously defined or configured timelineagain and repeat such an operation again.

In this case, the maximum number of re-transmissions which are possiblewith respect to the PUSCH transmission may be defined or configured.

When an operation is not defined (or supported or configured) in whichthe eNB sends the ACK or NACK with respect to initial PUSCH transmission(e.g., # n-th slot), the UE (assumes that the eNB normally receives theACK or the NACK) and initiates the subsequent PUCCH transmission.

However, when the UE receives, from the eNB, a UL grant indicating thePUSCH retransmission in the meantime (e.g., within a specificpre-defined or configured time interval after an initial PUSCH), the UEmay initialize all association operations (e.g., stop and newly startall transmitted PUCCHs) to performing the PUSCH retransmission.

Thus, as a method for recognizing whether the UL grant is ‘UL grantindicating retransmission’, it may be recognized that retransmission isindicated when the HARQ ID in the UL grant is the same, it may berecognized that retransmission is indicated whether to indicate the samereporting setting, or it may be recognized that retransmission isindicated by whether toggling is performed because a new data indicatorfield is included in the DCI similarly to the LTE system.

Additionally, for an operation of performing the CSI reporting by usingboth the PUSCH and the PUCCH, PUSCH resource allocation information,PUSCH resource allocation/selection information, and reportingactivation information may be signaled from the eNB to the UE togetheror separately.

For example, the reporting activation and the PUCCH allocation/selectioninformation may be together transmitted (through the MAC CE) and thePUSCH resource allocation information may be separately transmitted bythe DCI.

In this case, when the UE is allocated the PUSCH resource withoutperforming the CSI reporting until receiving the DCI for the PUSCHresource allocation from the eNB, the UE may perform the subsequent CSIreporting through the PUCCH resource after performing first CSIreporting through the PUSCH.

Alternatively, (2) the UE may start performing the CSI reporting throughthe (selected) PUCCH resource regardless of an instance of receivingPUSCH resource allocation information. In the case of (2), when the UEreceives, from the eNB, the PUSCH resource allocation for the CSIreporting at any instance, PUCCH based CSI reporting informationperformed after the PUSCH based CSI reporting may have the dependency onthe PUSCH based CSI reporting information.

In addition, the PUCCH based CSI reporting information performed beforethe PUSCH based CSI reporting may have no dependency on the PUSCH basedCSI reporting information.

The PUCCH resource disclosed in the present disclosure is collectivereferred to as a PUCCH time, frequency, code, and/or spatial resource.

Further, the PUCCH resource may be configured differently for eachinstance. For example, PUCCH resource information allocated at differentinstances may be configured or indicated in the form of the sequence.

It may be more preferable that candidate PUCCH resource information isconfigured as RRC information and through which PUCCH resource theindicated CSI reporting is performed may be more dynamically indicatedthrough Medium Access Control (MAC) Control Element (CE) and/or DCI.

UL Resource Indication for Semi-Persistent/Aperiodic Reporting

In applying the proposed schemes described above, the (NR) system maysupport both the PUCCH based SP reporting the PUSCH based SP reportingand the eNB may select or configure which UL resource the SP CSIreporting is to be performed by using.

When the UL resource designation is configured by the RRCsemi-statically, the UL resource designation may be included in theparameter of the reporting setting.

Alternatively, a method for more dynamically configuring the UL resourcedesignation by the L1 signaling or L2 signaling may also be possible.

In this case, a plurality of candidate UL resources may be previouslyRRC-configured in a plurality of reporting settings or a singlereporting setting.

The plurality of (candidate) UL resources may be included in one or aplurality of PUCCH resources and/or one or a plurality of PUSCHresources.

Among them, the eNB may be explicitly or implicitly designate throughwhich UL resource the CSI reporting is to be performed through the L1and/or L2 signaling.

As one example of implicit indication, (CSI) reporting may be performedto the PUCCH at the time of activation with DL DCI and designated to bereported to the PUSCH at the time of activation with UL DCI.

In a latter case (reporting to the PUSCH), subsequent (CSI) reportingmay be performed by using the PUCCH.

As another example of the implicit indication, a plurality of PUCCHresources having different reporting timing attributes is configured bythe RRC (e.g., different slot offset with same/integer-multiple period),which PUCCH resource is to be used may be indicated through indicationof the reporting timing.

As yet another example of the implicit indication, when DCI based SP CSIreporting is introduced (for contiguous CSI reporting at a predeterminednumber of times) and MAC CE based SP CSI reporting is also introduced(for persistent CSI reporting until the eNB is deactivated), it may bemore preferable that the DCI based SP CSI reporting is performed by thePUSCH and the MAC CE based SP CSI reporting is performed by the PUCCH.

In this case, when the SP CSI reporting is indicated by the DCI, aresource allocation (RA) field for the PUSCH may be togethertransmitted.

In addition, when a mechanism of a type which is automatically stoppedafter performing the CSI reporting at a predetermined number of times isdefined, a risk in DCI misdetection is weakened, and as a result, DCImay be advantageous, which may more rapidly activate the CSI reporting.

Contrary to this, in the case of an SP CSI reporting mechanism which ispersistently maintained until receiving the (CSI reporting) deactivationindication, the CSI reporting is not deactivated at the time of the DCImisdetection, and as a result, serious interference and powerconsumption of the UE may be caused. Therefore, it may be morepreferable to perform deactivation by the MAC CE.

In such a case, it may be implicitly transferred whether the UE is touse the PUCCH or whether the UE is to perform the SP CSI reporting byusing the PUSCH according to a container for transferring theactivation/deactivation message is the DCI or the MAC CE.

The L1/L2 explicit/implicit indication may be indicated together with orseparately from the CSI reporting activation message.

As a separately indicated example, the UL resource may be previouslyselected by the Layer 1 (L1) and/or Layer 2 (L2) signaling and then CSIreporting activation through the corresponding (or selected) UL resourcemay be indicated by subsequent L1 and/or L2 signaling.

The semi-static/dynamic UL resource selecting scheme may be applied evento the aperiodic CSI reporting in addition to the semi-persistent CSIreporting.

For example, one or a plurality of PUCCH resources and/or one or aplurality of PUSCH resources may be RRC-configured for the aperiodic CSIreporting and then a final UL resource that is to perform the aperiodicCSI reporting may be designated through L1 and/or L2 implicit orexplicit indication.

CSI Reporting Activation/Deactivation Timing

The PUSCH resource or PUCCH resource may be deactivated together at thetime of semi-persistent reporting deactivation.

In this case, with respect to the deactivation instance, (1) the CSIreport is not sent after the corresponding slot, (2) all remaining CSIfeedback parameters are transmitted and then the CSI reporting isstopped, or (3) the eNB may stop the CSI reporting after a configured(or designated) instance.

In the case of (2), CSI feedback information may be sequentially splitand transmitted through various reporting instances due to a limit inpayload size as in the LTE at the time of the CSI reporting through thePUCCH.

In this case, when the UE receives, from the eNB, the reportingdeactivation message in the middle of the reporting, the occupied PUSCHresource or PUCCH resource may be maintained until the remaininginformation is completely sent.

Alternatively, when the UE receives the reporting deactivation messageby the MAC CE, the UE may stop the reporting based on a slot whichreturns the ACK for the PDSCH for transmitting the MAC CE.

Alternatively, even though the UE receives the reporting deactivationmessage by the DCI, the ACK/NACK for the PDCCH may be defined.

Even in this case, the (CSI) reporting may be stopped based on the slotwhich returns the ACK.

In this case, even though the UE receives the reporting deactivationmessage in an n-th slot, the CSI reporting may be maintained until ann+k-th slot which is an ACK return instance.

Even in regard to the CSI reporting start instance, the CSI reportingmay be initialized after an instance determined based on a slot instanceof receiving reporting activation DCI (or reporting activation MAC CE)(or configured by the eNB) or the reporting may be initialized after aninstance determined based on a slot instance of transmitting the ACK forthe reporting activation DCI (or reporting activation MAC CE) (orconfigured by the eNB).

PUCCH/PUSCH Resource (Amount) Allocation for SP CSI Reporting

Next, a PUCCH or PUSCH resource allocating method for the SP CSIreporting will be described.

CSI reporting information may be separately transmitted several timesdue to the limit in payload size which may be transmitted at once at thetime of the SP CSI reporting.

For example, there may be CSI reporting on the PUCCH in the LTE orhybrid CSI feedback in Rel.14 LTE.

In this case, the CSI payload size to be sent at each reporting instancemay vary.

To this end, (1) a method of using only one PUSCH/PUCCH formatsupporting the same maximum payload size every CSI reporting instanceand (2) a method of using a plurality of different PUCCH/PUSCH formatssupporting different max payload sizes every CSI reporting instance maybe considered.

In the case of (1), a UL power control mechanism may be defined, inwhich since a UCI code rate may vary every CSI reporting instance, whena high code rate is used, power boosting is performed and when a lowcode rate is used, power de-boosting is performed.

Further, in the case of (2), an operation of the eNB whichsemi-statically/dynamically configures or designates the reportinginstance and the type of PUSCH/PUCCH format to be used may be required.

Alternatively, a PUSCH/PUCCH format change pattern may be defined whichis promised on the time according to a CSI feedback informationconfiguration (e.g., CSI reporting mode in LTE).

Similarly to the LTE PUCCH, CSI feedback parameters need to besubdivided into multiple groups and respective CSI parameter groups maybe sequentially transmitted through different PUCCH transmissioninstances due to the limit in CSI payload size on each PUCCH.

In the NR PUCCH, since consistency for the number of PUCCH symbols maynot be guaranteed due to a flexible TDD operation, the PUCCH resourceavailable for each CSI reporting instance may not be consistent.

Accordingly, in the case of CSI reporting for the PUCCH havingfragmented CSI parameters, unequal grouping of the CSI parameters may bepreferable in terms of the CSI payload size.

Hereinafter, a matter related to a PUCCH design for CSI reporting andbeam management will be described in brief.

A research into multi-beam based NR-PUCCH transmission for robustnessfor beam pair link blocking is performed.

For example, the UE may transmit the NR-PUCCH for different UL Tx beamsin different NR-PUCCH OFDM symbols.

A combination of a semi-static configuration (at least for specifictypes of the UCI information) and dynamic signaling is used fordetermining both the PUCCH resources for the ‘long PUCCH format andshort PUCCH format’.

Two NR-PUCCHs may be transmitted from one UE on the same slot by the TDMscheme.

Two NR-PUCCHs may be short PUCCHs.

Two NR-PUCCHs may be short PUCCH and short PUCCH.

PUCCH Resources for Different Time Domain Behaviors of CSI Reporting

In the LTE, since the maximum UCI payload size which is supportable inthe PUCCH is fixed and the CSI reporting is very limited, the CSIreporting for the PUCCH is supported only for light-weight CSI feedback.

The CSI feedback information is split into various portions due to thelimit in PUCCH payload size and sequentially transmitted to multiplePUCCHs in different subframes.

In addition, heavy and aperiodic CSI reporting is supported only in thePUSCH.

However, in the NR, the UCI payload size which is supportable on thePUCCH may be very wide according to a PUCCH type (i.e., PUCCH inlong-duration or PUCCH in short-duration) and the number of PUCCHsymbols (or PUCCH duration).

The maximum UCI payload size which is supportable in the PUCCH maysignificantly increase to several hundreds of bits in the case of thePUCCH (or long PUCCH) in the long-duration.

Accordingly, in the NR, wider and more flexible using the PUCCH may beconsidered for the CSI reporting.

As described above, in the NR, three time domain operations (aperiodic,semi-static (or semi-permanent or semi-persistent), and periodic CSIreporting) of the CSI reporting are supported.

The PUCCH may be used for periodic and semi-static CSI reportingsimilarly to the LTE.

However, in the case of the NR, the payload size of the CSI feedbackwhich is maximally supportable per CSI reporting instance is dynamic andit is almost impossible to maintain consistency for a flexible TDD slotconfiguration.

It is more preferable to permit different PUCCH formats/duration everyCSI reporting instance according to the CSI payload size in order toavoid excessive CSI fragmentation and reporting delay.

In this regard, as described above, commonly using the PUSCH and thePUCCH for the CSI reporting may also be considered.

For example, when the PUSCH is first used for the entire CSI feedback,the CSI feedback may be updated by using the PUCCH in the case of thesemi-static CSI reporting.

A PUCCH format/duration which is not matched per CSI reporting instancefor the semi-static/periodic CSI reporting is considered.

The aperiodic CSI reporting is supported only through the PUSCH in theLTE, but the aperiodic CSI reporting for the PUCCH may be considered inthe NR.

One of main motivations using the PUCCH for the aperiodic CSI reportingmay be, for example, immediate and fast CSI reporting in the slot.

The corresponding PUCCH for CSI triggering DCI, CSI-RS, and CSIreporting may exist in the same slot.

In this regard, the short PUCCH may be positioned at the end of the slotand since a maximum of two symbols are occupied, the PUCCH (or shortPUCCH) in the short duration may become an appropriate candidatesimilarly to fast ACK/NACK reporting.

Such a function may be supported only for very light CSI feedback byconsidering only a CSI calculation time.

Further, the aperiodic CSI reporting may be considered on the shortPUCCH for quick and very light CSI feedback.

FIG. 11 is a flowchart illustrating one example of an operation methodof a UE that performs SP CSI reporting proposed by the presentdisclosure.

First, the UE receives, from the eNB, downlink control information (DCI)indicating activation of semi-persistent (SP) CSI reporting (S1110).

Here, the uplink control information may be scrambled with a specificRNTI distinguished from a Cell-Radio Network Temporary Identity(C-RNTI).

Here, an advantage of using the RNTI separated from the C-RNTI is that amisdetection for the DCI of the UE may be reduced and the valid bit maybe added to the DCI.

Thereafter, the UE reports to the eNB the semi-persistent CSI throughthe physical uplink shared channel (PUSCH) based on the receiveddownlink control information (S1120).

Here, the SP CSI reporting may include first SP CSI reporting and secondSP CSI reporting.

As one example, when the quantity of SP CSI reports is large, the SP CSIreport may be separately transmitted several times and the second SP CSIreporting may be performed after the first SP CSI reporting.

Further, the UE may receive, from the eNB, the PUSCH resource to reportthe SP CSI before or after performing S1110.

Here, when the PUSCH resource collides with a specific uplink resource,the SP CSI may be reported to the eNB through the physical uplinkcontrol channel (PUCCH).

Specifically, when the PUSCH resource and the PUCCH resource to reportthe SP CSI collide with each other, the PUSCH resource to report the SPCSI may be dropped and the SP CSI (or by feeding back the SP CSI to thePUCCH) may be reported by using the collided PUCCH resource or aseparately configured PUCCH (for the CSI reporting).

Alternatively, when the PUSCH resource (mini-slot or one shot) and thePUSCH resource to report the SP CSI collide with each other, the PUSCHresource may be dropped (or not transmitted) and the SP CSI may bereported by using the collided PUSCH resource (mini-slot or one shot) ora separately configured PUCCH (for the CSI reporting). Here, themini-slot may mean a slot constituted by symbols of a specific number orless, which may be constituted by 2, 4, or 7 symbols.

In addition, the SP CSI through the PUCCH may be reported in a slotrelated to the collision.

Further, the UE may determine an uplink resource to perform the SP CSIreporting before performing step S1120.

Specifically, the UE may report the SP CSI through the PUSCH when theDCI is uplink DCI and report the SP CSI through the PUCCH when the DCIis downlink DCI.

The SP CSI reporting through the PUSCH described above is different fromSPS scheduling in LTE used for the purpose of the VoP service in thatthe SP CSI reporting may be used for the purpose of controllinginterference with a neighboring cell.

In addition, SP CSI transmission through the PUSCH is different from SPSscheduling that does not perform UL transmission when there is no datumto be transmitted in that the CSI is continuously transmitted orreported in the corresponding period with a predetermined period.

Overview of Devices to which Present Disclosure is Applicable

FIG. 12 illustrates a block diagram of a wireless communicationapparatus according to an embodiment of the present disclosure.

Referring to FIG. 12, a wireless communication system includes an eNB(or network) 1210 and a UE 1220.

The eNB 1210 includes a processor 1211, a memory 1212, and acommunication module 1213.

The processor 1211 implements a function, a process, and/or a methodwhich are proposed in FIGS. 1 to 11 above. Layers of a wired/wirelessinterface protocol may be implemented by the processor 1211. The memory1212 is connected with the processor 1211 to store various pieces ofinformation for driving the processor 1211. The communication module1213 is connected with the processor 1211 to transmit and/or receive awired/wireless signal.

The communication module 1213 may include a radio frequency (RF) unitfor transmitting/receiving a radio signal.

The UE 1220 includes a processor 1221, a memory 1222, and acommunication module (or RF unit) 1223. The processor 1221 implements afunction, a process, and/or a method which are proposed in FIGS. 1 to 11above. The layers of the wireless interface protocol may be implementedby the processor 1221. The memory 1222 is connected with the processor1221 to store various pieces of information for driving the processor1221. The communication module 1223 is connected with the processor 1221to transmit and/or receive the wireless signal.

The memories 1212 and 1222 may be positioned inside or outside theprocessors 1211 and 1221 and connected with the processors 1211 and 1221by various well-known means.

Further, the base station 1210 and/or the UE 1220 may have a singleantenna or multiple antennas.

FIG. 13 illustrates a block diagram of a communication device accordingto an embodiment of the present disclosure.

In particular, FIG. 13 is a diagram more specifically illustrating theUE of FIG. 12 above.

Referring to FIG. 13, the UE may be configured to include a processor(or a digital signal processor (DSP) 1310, an RF module (or RF unit)1335, a power management module 1305, an antenna 1340, a battery 1355, adisplay 1315, a keypad 1320, a memory 1330, a subscriber identificationmodule (SIM) card 1325 (this component is optional), a speaker 1345, anda microphone 1350. The UE may also include a single antenna or multipleantennas.

The processor 1310 implements a function, a process, and/or a methodwhich are proposed in FIGS. 1 to 11 above. Layers of a wirelessinterface protocol may be implemented by the processor 1310.

The memory 1330 is connected with the processor 1310 to storeinformation related to an operation of the processor 1310. The memory1330 may be positioned inside or outside the processor 1310 andconnected with the processor 1310 by various well-known means.

A user inputs command information such as a telephone number or the likeby, for example, pressing (or touching) a button on the keypad 1320 orby voice activation using the microphone 1350. The processor 1310receives such command information and processes to perform appropriatefunctions including dialing a telephone number. Operational data may beextracted from the SIM card 1325 or the memory 1330. In addition, theprocessor 1310 may display command information or drive information onthe display 1315 for the user to recognize and for convenience.

The RF module 1335 is connected with the processor 1310 to transmitand/or receive an RF signal. The processor 1310 transfers the commandinformation to the RF module 1335 to initiate communication, forexample, to transmit wireless signals constituting voice communicationdata. The RF module 1335 is constituted by a receiver and a transmitterfor receiving and transmitting the wireless signals. The antenna 1340functions to transmit and receive the wireless signals. Upon receivingthe wireless signals, the RF module 1335 may transfer the signal forprocessing by the processor 1310 and convert the signal to a baseband.The processed signal may be converted into to audible or readableinformation output via the speaker 1345.

FIG. 14 is a diagram illustrating an example of an RF module of thewireless communication device to which the method proposed in thepresent specification may be applied.

Specifically, FIG. 14 illustrates an example of an RF module that may beimplemented in a frequency division duplex (FDD) system.

First, in a transmission path, the processors described in FIGS. 12 and13 process the data to be transmitted and provide an analog outputsignal to the transmitter 1410.

Within the transmitter 1410, the analog output signal is filtered by alow pass filter (LPF) 1411 to remove images caused by adigital-to-analog conversion (ADC) and up-converted to an RF from abaseband by an up-converter (mixer) 1412, and amplified by a variablegain amplifier (VGA) 1413 and the amplified signal is filtered by afilter 1414, additionally amplified by a power amplifier (PA) 1415,routed through a duplexer(s) 1450/an antenna switch(es) 1460, andtransmitted through an antenna 1470.

In addition, in a reception path, the antenna 1470 receives signals fromthe outside and provides the received signals, which are routed throughthe antenna switch(es) 1460/duplexers 1450 and provided to a receiver1420.

In the receiver 1420, the received signals are amplified by a low noiseamplifier (LNA) 1423, filtered by a bans pass filter 1424, anddown-converted from the RF to the baseband by a down-converter (mixer)1425.

The down-converted signal is filtered by a low pass filter (LPF) 1426and amplified by a VGA 1427 to obtain an analog input signal, which isprovided to the processors described in FIGS. 12 and 13.

Further, a local oscillator (LO) generator 1440 also providestransmitted and received LO signals to the up-converter 1412 and thedown-converter 1425, respectively.

In addition, a phase locked loop (PLL) 1430 receives control informationfrom the processor to generate the transmitted and received LO signalsat appropriate frequencies and provides control signals to the LOgenerator 1440.

Further, circuits illustrated in FIG. 14 may be arranged differentlyfrom the components illustrated in FIG. 14.

FIG. 15 is a diagram illustrating yet another example of the RF moduleof the wireless communication device to which a method proposed bypresent disclosure can be applied.

Specifically, FIG. 15 illustrates an example of an RF module that may beimplemented in a time division duplex (TDD) system.

A transmitter 1510 and a receiver 1520 of the RF module in the TDDsystem are identical in structure to the transmitter and the receiver ofthe RF module in the FDD system.

Hereinafter, only the structure of the RF module of the TDD system thatdiffers from the RF module of the FDD system will be described and thesame structure will be described with reference to a description of FIG.14.

A signal amplified by a power amplifier (PA) 1515 of the transmitter isrouted through a band select switch 1550, a band pass filter (BPF) 1560,and an antenna switch(es) 1570 and transmitted via an antenna 1580.

In addition, in a reception path, the antenna 1580 receives signals fromthe outside and provides the received signals, which are routed throughthe antenna switch(es) 1570, the band pass filter 1560, and the bandselect switch 1550 and provided to the receiver 1520.

In the embodiments described above, the components and the features ofthe present disclosure are combined in a predetermined form. Eachcomponent or feature should be considered as an option unless otherwiseexpressly stated. Each component or feature may be implemented not to beassociated with other components or features. Further, the embodiment ofthe present disclosure may be configured by associating some componentsand/or features. The order of the operations described in theembodiments of the present disclosure may be changed. Some components orfeatures of any embodiment may be included in another embodiment orreplaced with the component and the feature corresponding to anotherembodiment. It is apparent that the claims that are not expressly citedin the claims are combined to form an embodiment or be included in a newclaim by an amendment after the application.

The embodiments of the present disclosure may be implemented byhardware, firmware, software, or combinations thereof. In the case ofimplementation by hardware, according to hardware implementation, theexemplary embodiment described herein may be implemented by using one ormore application specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, micro-controllers, microprocessors,and the like.

In the case of implementation by firmware or software, the embodiment ofthe present disclosure may be implemented in the form of a module, aprocedure, a function, and the like to perform the functions oroperations described above. A software code may be stored in the memoryand executed by the processor. The memory may be positioned inside oroutside the processor and may transmit and receive data to/from theprocessor by already various means.

It is apparent to those skilled in the art that the present disclosuremay be embodied in other specific forms without departing from essentialcharacteristics of the present disclosure. Accordingly, theaforementioned detailed description should not be construed asrestrictive in all terms and should be exemplarily considered. The scopeof the present disclosure should be determined by rational construing ofthe appended claims and all modifications within an equivalent scope ofthe present disclosure are included in the scope of the presentdisclosure.

INDUSTRIAL APPLICABILITY

In the wireless communication system of the present disclosure, anexample in which the CSI reporting method is applied to the NR systemand the 5G system is primarily described, but besides, the CSI reportingmethod may be applied to various wireless communication systems.

The invention claimed is:
 1. A method for reporting, by a user equipment(UE), channel state information (CSI) in a wireless communicationsystem, the method comprising: receiving, from a base station, CSIreporting configuration via a first radio resource control (RRC)signaling, the CSI reporting configuration comprising information for atime domain CSI reporting behavior configured as semi-persistent (SP);receiving, from the base station, a downlink transmission related to anactivation of SP CSI reporting; and transmitting, to the base station,an SP CSI report based on the time domain CSI reporting behaviorconfigured as SP in the CSI reporting configuration, wherein based onthe downlink transmission including downlink control information (DCI)that indicates the activation of the SP CSI reporting, the SP CSI reportis transmitted to the base station on a physical uplink shared channel(PUSCH), and wherein based on the downlink transmission including amedium access control (MAC) control element (CE) that indicates theactivation of the SP CSI reporting, the SP CSI report is transmitted tothe base station on a physical uplink control channel (PUCCH).
 2. Themethod of claim 1, wherein the SP CSI reporting includes a first SP CSIreporting and a second SP CSI reporting.
 3. The method of claim 1,further comprising: based on the downlink transmission including the DCIthat indicates the activation of the SP CSI reporting: receiving, fromthe base station, resource configuration information related toscheduling a PUSCH resource for transmitting the SP CSI report.
 4. Themethod of claim 3, wherein based on the downlink transmission includingthe DCI that indicates the activation of the SP CSI reporting: based ona collision between the PUSCH resource and a specific uplink resource,the SP CSI report is transmitted to the base station through the PUCCH.5. The method of claim 4, wherein the specific uplink resource isanother PUCCH resource or another PUSCH resource on a mini-slot.
 6. Themethod of claim 4, wherein the SP CSI report is transmitted through thePUCCH in a slot which is related to the collision between the PUSCHresource and the specific uplink resource.
 7. The method of claim 1,further comprising: determining an uplink resource on which to transmitthe SP CSI report.
 8. The method of claim 1, wherein based on thedownlink transmission including the DCI that indicates the activation ofthe SP CSI reporting: the DCI is scrambled with a specific radio networktemporary identity (RNTI) which is distinct from a cell-radio networktemporary identity (C-RNTI).
 9. A user equipment (UE) configured toreport channel state information (CSI) in a wireless communicationsystem, the UE comprising: a transceiver; and at least one processor;and at least one computer memory operably connected to the at least oneprocessor and storing instructions that, based on being executed by theat least one processor, perform operations comprising: receiving, from abase station through the transceiver, CSI reporting configuration via afirst radio resource control (RRC) signaling, the CSI reportingconfiguration comprising information for a time domain CSI reportingbehavior configured as semi-persistent (SP); receiving, from the basestation through the transceiver, a downlink transmission related to anactivation of SP CSI reporting; and transmitting, to the base stationthrough the transceiver, an SP CSI report based on the time domain CSIreporting behavior configured as SP in the CSI reporting configuration,wherein based on the downlink transmission including downlink controlinformation (DCI) that indicates the activation of the SP CSI reporting,the SP CSI report is transmitted to the base station on a physicaluplink shared channel (PUSCH), and wherein based on the downlinktransmission including a medium access control (MAC) control element(CE) that indicates the activation of the SP CSI reporting, the SP CSIreport is transmitted to the base station on a physical uplink controlchannel (PUCCH).
 10. The UE of claim 9, wherein the SP CSI reportingincludes a first SP CSI reporting and a second SP CSI reporting.
 11. TheUE of claim 9, wherein the operations further comprise: based on thedownlink transmission including the DCI that indicates the activation ofthe SP CSI reporting: receiving, from the base station through thetransceiver, resource configuration information related to scheduling aPUSCH resource for transmitting the SP CSI report.
 12. The UE of claim11, wherein based on the downlink transmission including the DCI thatindicates the activation of the SP CSI reporting: based on a collisionbetween the PUSCH resource and a specific uplink resource, the SP CSIreport is transmitted to the base station through the PUCCH.
 13. The UEof claim 12, wherein the specific uplink resource is another PUCCHresource or another PUSCH resource on a mini-slot.
 14. The UE of claim12, wherein the SP CSI report is transmitted through the PUCCH in a slotwhich is related to the collision between the PUSCH resource and thespecific uplink resource.
 15. The UE of claim 9, wherein the operationsfurther comprise: determining an uplink resource on which to transmitthe SP CSI report.
 16. The UE of claim 9, wherein based on the downlinktransmission including the DCI that indicates the activation of the SPCSI reporting: the DCI is scrambled with a specific radio networktemporary identity (RNTI) which is distinct from a cell-radio networktemporary identity (C-RNTI).